Hi HK,
Sorry you have to be here dealing with a fistula but welcome.
I also suffered an abscess that turned into a fistula. I caught it very quickly - the moment the abscess popped, I was well aware of the possibility of a fistula development and was able to almost self-diagnosis immediately and I know that helped me a lot because it was a lot easier to catch & treat. I needed no more than a simple fistulomy, which took 20 mins to fix with an uncomplicated recovery process. Nearly 2 years on, I'd never have know I had this issue.
I really do believe that the quicker you start dealing with these things, the better your situation.
It could be that even though your CRS believes it could be more complicated, that it could be nothing more than a fistulomy that will help you sort this - A seton will be inserted if the fistula tract interacts with the internal sphincter muscle but a lot of people have these and recover very successfully. They can be a little uncomfortable to get used to but most people find them less bothersome after a while and then of course, they come out anyway. Sometimes the Seton will be inserted straightaway and then the Fistulomy performed once the drainage process seems to be complete, but these are nothing to worry about. Even if your fistula is draining a lot now, they will still use a seton if the tract goes through the sphincter.
Hopefully you will find that post-surgery will be no less painful than before & you should go on to make a full recovery once all the nastiness has been removed and cleared.
My fistula also never bothered me to a huge extent - my biggest discomfort was the inflammation when the opening began to fill with pus in that cycle - once it started to drain again, there was always relief and I hoped it would just go away, only it never did, which made me believe that you can't heal these things without surgery.
It's always a little uncomfortable of course after the surgery, but nothing majorly painful, and you will need to make sure you are keeping your stools nice and soft through good eating and lots of liquids, so as to minimise any pressure from straining when you go for a BM, but taking a stool softener for a few weeks whilst you recover will also help a lot.
I returned to work 10 days after my op and was actually OK. It was a little uncomfortable getting in and out of my car - I think that was the most uncomfortable part for me but I felt absolutely fine otherwise. If your process is straight forward, then 8 days should be OK but just make some alternative plans if you can, just in case the surgery is more complex, as it's good to get that recovery time after (more than anything just to use the comforts of your own bathroom!)
Full recovery time depends on the individual, the surgery etc. but if everything is straightforward, it can take around 4-6 weeks for a fistula wound to fully heal (although you can resume normal activities long before this!)
It might be helpful to rest up as much as you can afterwards but you should be able to resume your activities pretty quickly afterwards - I'm guessing you might be advised a couple of weeks rest but it shouldn't hinder your Volleyball for too long!
Sex is absolutely fine with a seton too - It depends on how you feel and how conscious you are about it all but the seton itself won't cause issues with that process - it really is up to how comfortable you feel in yourself and when you feel the time is right for you again.
Hopefully, because this was caught so soon, your surgery & recovery will not be so long and they can sort you out pretty quickly - some fistulae lie undetected for a long time and it tends to be these that can create on-going issues with multiple surgeries.
I would just say try not to worry too much at all and take each day as it comes - Fistula surgery is not the worst & most painful surgery you could be facing & within a few months, hopefully, it should all be sorting itself out for you. Feel free to pop back any time for more info! & all the very best to you :)
All the very best with your forthcoming surgery!!